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Groundwater Explorations

The movement and presence of groundwater is one of the main parameters that change the electrical resistivity of geological units. Electrical Resistivity Tomography (ERT) is one of the most indisputable geophysical methods, providing 2D and 3D images of the ground and guiding the identification of groundwater aquifer points and accurate drilling operations.

Although vertical electrical drilling VES (1-D measurements) is often used as an inexpensive method in groundwater investigations, especially in developing countries, the low resolution of this method is unlikely to provide reliable results today. For aquifer zones and heterogeneous sedimentary aquifers, it is now a proven fact that 2D and 3D ERT techniques can provide higher resolution and more reliable data by utilizing current technology.

In addition, geophysical well logs are actively used in our country today to increase groundwater yield. It is currently used in determining the fractured and fractured aquifer points in the well in cm level, determining the filter points of the pimash pipe to be thrown into the well and planning the depth of the submersible pump to be thrown into the well.

SAGTech Geophysics provides the most accurate results to its customers by integrating geophysical data with the most ideal geological models by using up-to-date geophysical technologies, using geophysical techniques effectively for groundwater points, aquifer areas and groundwater yield quality with its expert team.

    Groundwater Exploration Areas

    • Determination of aquifer points in mine sites
    • Determination of groundwater zones and depths
    • Determination of salt water intrusion and saline-fresh water separation
    • Identification of groundwater contaminants

    Geophysical Methods We Use

    • SP (Natural Potential)
    • VES (Vertical Electrical Drilling)
    • IP/Resistivity (2D-3D ERT)
    • Electromagnetic (MT-AMT)
    • Geophysical Well Logs
    Caliper Log

    Records the variation of the borehole diameter. Changes in borehole diameter are related to well structure, such as casing or drill bit size, and fracture or collapse along the borehole wall. Because borehole diameter often affects log response, the caliper log is useful in analyzing other geophysical logs, including the interpretation of flowmeter logs.

    Natural Gamma Log

    It records the amount of natural gamma radiation emitted by the rocks surrounding the borehole. The most important naturally occurring sources of gamma radiation are potassium-40 and the products of the uranium and thorium decay series. Rocks containing clay and shale often emit relatively high gamma radiation because they contain weathering products of potassium feldspar and mica and tend to concentrate uranium and thorium through ion absorption and exchange.

    SP / Rezistivite Logu

    The Resistivity Log measures resistance (instead of resistivity) with 2 current electrodes and 2 measuring electrodes. 3 different configurations: short-normal, long-normal and lateral. The short-normal has the smallest distance between 2 adjacent electrodes (16 inches). It is the most sensitive to thin layers but is also affected by drilling mud. Side log has the longest distance (18 feet 8 inches) between two adjacent electrodes. Resistance samples are taken over a large sediment/rock section away from the borehole. The lateral log can miss thin deposits.

    The SP Log is measured between a soil electrode at the surface and an electrode lowered into the well. Shale has a positive SP response and sand has a negative SP response when the formation water is saltier than the drilling mud.

    Flow Meter Log

    Records the direction and velocity of vertical flow in the borehole. Borehole flow rates can be calculated from downhole velocity measurements and borehole diameter recorded by the caliper log. Flow meter logs can be categorized under non-pumping and/or pumping conditions. Impeller flowmeters are the most commonly used but are generally unable to resolve velocities below 5 m/min. Heat pulse and electromagnetic flowmeters can resolve velocities below 0.1 m/min.

    Acoustic Televiewer Log (ATV)

    It records a magnetically oriented, photographic image of the acoustic reflection of the borehole wall. Televiewer logs show the position, orientation and dip of fractures and lithologic contacts. The collection of televiewer logs is limited to open holes filled with water or mud.

    Optical Televiewer Log (OTV)

    They are widely used in groundwater surveys to inspect the condition of well casing and screens; they can also be used to directly image lithological texture, grain size and color, water levels and bedrock fractures. Television recordings can be obtained in clear water and above the water table. The most advanced television systems are magnetically oriented and provide a 360-degree digital image of the borehole wall.

    Fluid Log

    Records the electrical resistivity of the water in the borehole. Changes in fluid resistivity reflect differences in the dissolved solids concentration of the water. Fluid resistivity logs are useful in identifying water-bearing zones and defining vertical flow in the borehole.